Facebook Page Management

I'm going to be helping a friend w/ their Facebook business page. They are very clueless about all things Facebook and I'm worried if I send them the instructions to assign roles to me in their Facebook page they won't understand them.

If I get their personal logins, hop in to their Facebook page and assign myself as an admin on the page will it cause issues? --- The IP address will obviously be 'foreign' and I'm wondering if that will cause issues.

What's the best way to go about this?

no if your accounts are old it won't cause issues
but just show them how to add you on that page. it is safer

just use teamviewer, go on their computer and do what you need

or use screencast extention on chrome and make a video how to do it! you in 50 second done.